Centrifugal pump impeller



28, 1932. y M M, KLOSSON 1,864,834

CENTRIFUGAL -PUMP IMPELLER Filed Deo. 28, 1927 A fr0/M096;

Patented June 2s, 1932 UNITED ASTATES PATENT OFI-IcaA A MICHAEL M. xLossoN, or xENMonE, NEW Yonx, AssIGNoR rr'o BUFFALO STEAM PUMP COMPANY, oF BUFFALO, NEW YORK CENTRIPUGAI. PUMP IMPELLER Application inea December as, 1927. seran No. 243,149.

This invention relates to impellers for centrifugal pumps and more particularly for pumps of the kind adapted for pumping liquid containing solidV or semisolid materials, such for 'example as paper stock, sewage, sludge or the like.

In using a centrlfugalpump in connection Y with liquids containing solids or semisolids,

nection with the-pumping of liquids containn ing wood pulp or similar materials, it has been found that the wood pulp or other material tends to collect in the inlet end of the pump about the axis of rotation of the im peller and to form a more or less compacted mass while the liquid is carried away by the Y vanes of the impeller, the formation of this mass being helped by the rounded or very blunt forward ends of the vanes, which tend to roll or compact the mass, until eventually the pump'becomes plugged or stopped by this accumulation of material. It is then necessary toremove this accumulation before the pump can again be operated.` 'In pumps having relatively thin impeller vanes this -accumulation of materials does not occur, probably due to the fact that the comparatively Y sharp forward ends of the vanes cut material from the mass and thus prevent clogging of the pump, but such vanes collect material on the forward ends thereof as above stated.

Y The objects of this invention are to provide a centrifugal pump in whichthev vanes are provided with convexly curved forward ends and portions at their forward ends which extend toward the center of rotation to prevent the formation of a mass of material at 45 rounded so as to prevent the material which is being pumped from adhering to the projections of the forward endsofthe vanes; also to so shape the projections on the forward ends of the vanes as not to interfere with the operation and efficiency of the pump.; also to provide a pump of this kind with vanes of improved construction having enlarged forward ends and comparatively thin outwardly extending portions; also to improve the construction of pumps of this kind 1n other respects hereinafter specified.

In the accompanying drawing,

Fig. l is a vertical sectional elevation of Y a'pump having an impeller embodying my invention, the impeller of the pump being shown in elevation.

F 1g. 2 is a face view of the impeller on an enlarged scale.

Fig. 3 is a section thereof on line 3-3,

Fig. 2.

Fig. 4: is a section thereof on line 4--4, Fig. 2. Y

Fig. 5 is a face view of an impeller of modified construction. f

Referring to Fig. l of the drawing, A represents the base or support on whichthe pump is mounted and which provides suitable journals for the pump shaft B. C represents the housing or shell of the pump and D represents the side plate which partl closes the housing at the suction end thereo and having an inlet-or suction aperture ai therein. The impeller E may be mounted on the end ofV the shaft B in any usual'or desired manner.

The impeller E shown in Figs. l to et Ais of the open type having a single radial vane supporting wall, disk or plate l0 provided with a central hub l1 byA means of which the impeller may be mounted on the shaft B of the pump. The vanes of the impeller are formed integralwith the wall or plate l0 and extend outwardly from this wall or plate toward the suction end of the pump. It will be obvious, however, that the invention may equally well be applied to an impeller of the enclosed type, in which case the usual second annular wall would connect the outer edges of the vanes. The vanes in the particular construction shown in Figs. 1 to 4L include relatively thin portions 12 which extend from the outer portion of the impeller toward the axis of the impeller. rlhese portions of the vanes correspond in shape somewhat to the vanes ordinarily used in centrifugal pumps. The forward ends of these vanes are, however, rounded and enlarged as indicated at 14, which enlarged portions are preferably substantially circular in cross section and which may be solid or may be made hollow as shown, thus providing a central cavity or aperture 15 extending substantially parallel with the axis of the impeller. The forward end of the reduced portion 12 of the vane preferably extends tangentially with reference to .the rounded enlarged portion 14. An impeller of this kind facilitates the manufacture of these impellers since the patterns from which the'impellers are cast can be readly changed to render them usable for pumps of different capacity or of different characteristics. For example a pump of smaller capacity may be made by-simply reducing the diameter of the impeller to fit a smaller housing, the reduction in diameter cutting ofi' the outer ends 'of the vanes without requiring any other change in the impeller vanes. By making the forward ends of the impellers closed at all sides the flow of liquid along both sides of the vanes is facilitated and also the gathering within the cavity 15 of material contained in the liquid which is being pumped, due to suction or eddy currents produced during the operation of the pump, is prevented. The collection of such material in the recesses in the enlarged rounded front end might readily effect the unbalancing of the impeller and cause vibration and injury to the pump and furthermore these eddies would tend to decrease the efficiency of the pump. By causing the walls of the enlarged rounded forward end of the pump to merge into the portion 12 of the vane as indicated at 16, the

formation of eddies of this kind is prevented.

In order to prevent the accumulation of solid or semi-solid material about the axis of rotation of the impeller, I provide the -forward ends ofthe vanes of the impeller with inclined or sloping forward portions or projections which slope or taper in such a manner that these projections are of greatest cross sectional area at the portions thereof adja- 1 cent to the plate or wall l0 and of least cross section at the portions thereof adjacent to the edges of the vanes adjacent to the suction or inlet portion of the pump. These proj ecions also extend inwardly toward the axis of rof tation from the forward ends of the vanes.

The projections 17 illustrated are preferably rounded on their forward edges so as to prevent the adhering of foreign material thereto, but the rounding of the forward edges of the v projections is not essential to the prevention of accumulation of material at the inlet passage of the pump adjacent to the axis of the impeller.

' In the modified construction shown in Fig.

and which have rounded forward ends 21.

The impeller shown in Fig. 5 also is provided with projections 22 at the forward ends of the vanes, which projections `correspond substantially with the projections 17 illustrated in Figs. 1 to 4 and function in the same manner. Projections of this :kind may be used on the forwardends of vanes of other constructions.

' I have found that by using in a pump used for pumping wood fibre or paper stock, an impeller Vprovided with vanes of this kind and having projections on the forward ends of the vanes substantially as shown and described, the Yaccumulation of a. mass of material in the suction end of the pump and also the stoppage ofthe pump because. of such accumulations was entirely eliminated.

1. A centrifugal pump impeller -vane having a narrow portion extending from the outer portion of the impeller toward vthe axis of the impeller and Vterminating in an ing a narrow portion extending from the outer portion of the impeller toward the axis of the impeller and terminating in an abrutly enlarged forward end which is convexly curved and which merges into the opposite faces of said narrow portion and which has an aperture therein extending substantially parallel with the axis of the impeller.

3. A centrifugal pump impeller vane having a narrow portion extending 'from the outer portion of the impeller towardthe axis of the impeller and having an enlarged forward end which is convexly curved and which merges into said narrow portion, saidnarrow portion extending tangentiallv with reference to said forward end.

4. A centrifugal lpump impeller vane -having a narrow portion extending from the outer'portion of theimpeller towardthe axis of the impeller and terminating in an abruptr lic of the pump, said projections terminating short of the axis of the impeller.

6. A centrifugal pump impeller vane having a rounded forward end and a projection on said forward end tapering axially toward the inlet of the pump and extending toward the axis of rotation of the impeller and terminating at a distance from said axis to leave the middle portion of the impeller free from any part tending to impart rotary motion to the liquid being pumped.

7. A centrifugal pump impeller including a vane supporting wall, and vanes extending from said wall toward the inlet end of the pump, each of said vanes having a convexly curved forward end provided with a projection extending from said forward end spirally toward the axis of rotation of the impeller, said p-rojection being of greatest cross sectional area immediately adjacent to said wall and tapering toward and terminating adj acent to the portion of the vane farthestfremoved from said Well, said projection terminating at a distance from the axis of said impeller and leaving the middle portion 0f said supporting wall free from any projecting past tending to impart rotary motion to liquid in the axial portion of the impeller.

8. A centrifugal pump impeller vane having a narrow portion of substantial uniform thickness extending from the outer portion of the impeller toward the axis of the impeller and having an enlarged forward end which is convexly curved and which merges into said narrow portion, said forward end having a projection tapering toward the inlet end of the pump and which extends forwardly and toward the axis o-f said impeller.

MICHAEL M. KLOSSON. 

